Calling a customer "Miss Piggy" and telling her in an email she was "rude and self-important" were sufficient reasons for a Wellington liquor store worker to be sacked, the Employment Relations Authority has ruled.

John Chan was dismissed as a duty manager at Miramar Liquorland after the customer reported his email to management.

Mr Chan told the customer he regretted not asking her to leave the store. He also said he was reminded of the Aaron Gilmore controversy, in which the disgraced politician acted rudely and attempted to have an employee reprimanded for not immediately tending to his needs.

Mr Gilmore resigned from Parliament last year after he was rude to a waiter during a boozy night in Hanmer Springs.

The customer initially complained about Mr Chan's rudeness on June 8 last year. Mr Chan then emailed the customer on June 28.

After his dismissal, he sought lost wages and compensation for hurt and humiliation for unjustified dismissal. However, the case was thrown out by Employment Relations Authority member Trish MacKinnon, who described his email as "disparaging and belittling".

Replying to questions about his email to the customer, Mr Chan wrote: "I believed that I no longer had my job, so in response to viewing Miss Piggy's complaint . . . I replied to her directly."

At an earlier disciplinary meeting, Mr Chan also said he had felt he had "nothing to lose" when he emailed the customer on June 28.

He said she was "stirring things up" and that "there was such a thing as free speech".

Ms MacKinnon found Mr Chan's dismissal was justifiable, saying business director Mark Satherley had given the worker ample time to respond to the allegations against him.